1. Field of the Invention
The present invention relates to a magnetic head device having a magnetic function part in a slider opposed to a magnetic recording medium such as a hard disk. More particularly, the invention relates to a magnetic head device which can suppress a variation in floating distance from the recording medium due to a change in air density.
2. Description of the Related Art
As a magnetic head device which records a magnetic signal on a magnetic recording medium such as a hard disk and reads the magnetic signal recorded on the magnetic recording medium, there is a type having a slider opposed to the magnetic recording medium and a magnetic function part disposed at a trailing end of the slider. The magnetic function part has a reproduction function part that makes use of an MR effect, a GMR effect, or a TMR effect and a recording function part in which a yoke of a magnetic material, a coil, etc. are formed of a thin film.
The slider of the magnetic head device is pressed to a surface of the magnetic recording medium by an elastic member called a loading beam. When the magnetic recording medium rotates, the slider floats from the recording medium by an airflow (air bearing) introduced between the surface of the recording medium and the slider, thereby setting a given floating amount between the magnetic function part and the recording medium.
Patent Documents 1 and 2 disclose a magnetic head device in which a front positive pressure surface, a rear positive pressure surface, and a pair of side positive pressure surfaces are provided on a recording medium-facing side of a slider. The front positive pressure surface is located close to a leading end and generates a floating pressure by an airflow, the rear positive pressure surface is located close to a trailing end and also generates a floating pressure, and the side positive pressure surfaces are located closer to the trailing end than the front positive pressure surface and spaced apart from each other in a transverse direction.
In this magnetic head device, a floating pressure acting on the front and rear positive pressure surfaces is utilized to stabilize a floating posture of the slider with a given pitch angle where the leading end face is lifted higher than the trailing end face, while a floating pressure acting on the left and right side positive pressure surfaces is utilized to stabilize a posture of the slider in a rolling direction. This aims at properly setting a floating distance of a magnetic function element, which is disposed close to the trailing end of the slider, from the recording medium.
Patent Document 1:
Japanese Unexamined Patent Application Publication No 2004-55127
Patent Document 2:
Japanese Unexamined Patent Application Publication No 2005-285218
In recent magnetic head devices, the floating amount of the magnetic function part from the recording medium is set as small as possible in order to improve magnetic recording density of the magnetic recording medium and achieve higher recording speed and reproduction speed of the magnetic signal. However, when reducing the floating distance of a slider from a magnetic recording medium, the floating amount easily reduces in response to a decrease in air density corresponding to a change in altitude. As a result, the slider is liable to contact the surface of the recording medium when it is used at a high altitude or in an airplane.
In the magnetic head device disclosed in Patent Documents 1 and 2, since the floating pressure acting on all the positive pressure surfaces of the slider, i.e., the front positive pressure surface, the rear positive pressure surface and the side positive pressure surfaces, decreases with a decrease in air density, the floating distance of the slider tends to extremely reduce, causing the problem that the slider contacts the recording medium.